It is known from British Patent Specification No. 1,355,917 that methyl acrylate can be dimerized to linear mono-unsaturated dimethyl dicarboxylates in the presence of a divalent palladium complex in combination with a quinone. Such linear esters are important intermediates for the production of polymers. However, this known dimerization proceeds rather slowly.
It is known from Tetrahedron Letters No. 4 (1979) 343-344, that methyl acrylate can be dimerized to linear mono-unsaturated dimethyl dicarboxylates in the presence of palladium(II) dichloride complexed with triphenylphosphine. It is stated that the rate of dimerization is increased by adding silver-fluoroborate. The Applicant has found that conversion is low in this known process and that metallic silver is formed.
It is an object of the present invention to provide a process exhibiting an increased rate of reaction and in which a catalyst is used which remains stable, yet producing dimers having a high linearity.